An electrophotographic photosensitive member using an organic photo-conductive material (organic electrophotographic photosensitive member) has been intensively studied and developed in recent years.
The electrophotographic photosensitive member basically includes a support and a photosensitive layer formed on the support. In actuality, however, various layers are provided in many cases between the support and the photosensitive layer for the purposes of, for example, covering defects of the surface of the support, protecting the photosensitive layer from electrical destruction, enhancing chargeability, and improving charge injection blocking property from the support to the photosensitive layer.
Of the layers to be provided between the support and the photosensitive layer, a layer containing a metal oxide particle is known as a layer to be provided for the purpose of covering defects of the surface of the support. The layer containing a metal oxide particle generally has high conductivity (for example, a volume resistivity of 1.0×108 to 5.0×1012 Ω·cm) as compared to that of a layer not containing metal oxide particle, and even when the thickness of the layer is increased, a residual potential at the time of forming an image is difficult to increase. Therefore, the layer containing a metal oxide particle covers defects of the surface of the support easily. When such layer having high conductivity (hereinafter, referred to as “conductive layer”) is provided between the support and the photosensitive layer to cover defects of the surface of the support, an allowable range of defects of the surface of the support is enlarged. As a result, an allowable range of the support to be used is enlarged. Thus, an advantage of enhancing productivity of an electrophotographic photosensitive member is provided.
Patent Literature 1 discloses a technology including using a tin oxide particle doped with phosphorus in an intermediate layer between a support and a photo-conductive layer. Further, Patent Literature 2 discloses a technology including using a tin oxide particle doped with tungsten in a protective layer on a photosensitive layer. Further, Patent Literature 3 discloses a technology including using titanium oxide particle coated with oxygen deficient tin oxide in a conductive layer between a support and a photosensitive layer. Further, Patent Literature 4 discloses a technology including using a barium sulfate particle covered with tin oxide in an intermediate layer between a support and a photosensitive layer.